Alfvén resonator
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An Alfvén resonator or Ionosphere Alfvén resonator is a spectral resonance structure found within geomagnetic fields in the frequency range of 0.1–10 Hz.[1] First reported in 1989, they are ionospheric short-period geomagnetic variations primarily seen as nighttime phenomena and rarely observed during the day.[2] The nighttime preference is due to lower electrical conductivity in the ionospheric dynamo region, which enables the feedback instability. [3]
